libprotobuf-mutator_fuzzing_learning

Learn how to combine libprotobuf-mutator with libfuzzer & AFL++

Environment Settings

• Ubuntu Linux 22.04 64 bit
• Clang 14.0.0
• libprotobuf-mutator 3.21.7 (af3bb1)

[!IMPORTANT] As of 2023/12/01, this repo won't work with the latest libprotobuf-mutator. It is recommended to switch to commit af3bb1 before compile & installing the libraries ( reference ).

• AFL++ 4.09a (61e27c)

Install Clang/LLVM & libfuzzer

• Follow the step in this article and add the toolchain's apt repository in Ubuntu.
• sudo apt-get install clang-14 libfuzzer-14-dev

Install libprotobuf-mutator

Follow the step in libprotobuf-mutator's readme

Install dependencies

sudo apt-get update
sudo apt-get install protobuf-compiler libprotobuf-dev binutils cmake \
  ninja-build liblzma-dev libz-dev pkg-config autoconf libtool

Build the required libraries

cd libprotobuf-mutator
mkdir build
cd build
( A cmake command, check the below section )
ninja # build the libraries
sudo ninja install # install the libraries ( optional )

About cmake command :

• Use the following cmake command to build libprotobuf-mutator-libfuzzer.so.0 and libprotobuf-mutator.so.0 shared library :

 cmake .. -GNinja -DCMAKE_C_COMPILER=clang-14 \ 
 -DCMAKE_CXX_COMPILER=clang++-14 \ 
 -DCMAKE_BUILD_TYPE=Debug \ 
 -DLIB_PROTO_MUTATOR_DOWNLOAD_PROTOBUF=ON \ 
 -DBUILD_SHARED_LIBS=ON

• To build static libraries ( libprotobuf-mutator-libfuzzer.a and libprotobuf-mutator.a ), use the following cmake command ( this will generate libraries that can be linked into shared libraries / normal program ) :

cmake .. -GNinja -DCMAKE_C_COMPILER=clang-14 \
-DCMAKE_CXX_COMPILER=clang++-14 \
-DCMAKE_BUILD_TYPE=Debug \
-DLIB_PROTO_MUTATOR_DOWNLOAD_PROTOBUF=ON \
-DCMAKE_C_FLAGS="-fPIC" -DCMAKE_CXX_FLAGS="-fPIC"

After building successfully, you can go to the build directory, and use the following command to check if the library is built correctly :

# Check if libprotobuf-mutator.so.0 exist
# To check other libraries just change the library name
find . | grep "libprotobuf-mutator.so.0"

How to upgrade the environment

• Upgrade Clang/LLVM & libfuzzer ( install a new version )
• Upgrade AFL++ ( git pull & rebuild )
• Upgrade libprotobuf-mutator ( git pull & rebuild )
  • Rebuild and re-install libprotobuf-mutator-libfuzzer.so.0 and libprotobuf-mutator.so.0.
  • Rebuild libprotobuf-mutator-libfuzzer.a and libprotobuf-mutator.a.
• Re-compile the protobuf with newer protoc and replace those *.cc & *.h with new ones.

FAQ

Q : I ran into this error message while building the binary : This file was generated by an old version of protoc.
A : If your protoc's version is newer, make sure to re-generate test.pb.cc and test.pb.h with the original protobuf source code test.proto ( source code and steps to generate *.cc & *.h are all in 1_simple_protobuf ).

Learning

• Simple protobuf example
• libprotobuf + libfuzzer
• libprotobuf + libfuzzer ( custom mutator )
• How to combine libprotobuf-mutator and AFL++
• Handling input samples from AFL++ in custom mutator

Reference

• libprotobuf-mutator
• Deconstructing LibProtobuf/Mutator Fuzzing
• Custom Proto Mutation
• AFL++ custom mutator
• afl-libprotobuf-mutator
• Advanced binary fuzzing using AFL++-QEMU and libprotobuf: a practical case of grammar-aware in-memory persistent fuzzing
  • ref1
  • ref2
  • ref3

LICENSE

MIT